Field of the Invention
The present invention relates to a biotechnological method and cell for producing at least one fatty acid ester from a sugar.
Discussion of the Background
Fatty acid esters may be used for several purposes commercially. For example, biodiesel, an alternative fuel, is comprised of esters (e.g., fatty acid methyl ester, fatty acid ethyl esters, etc.). Some low molecular weight esters are volatile with a pleasant odour which makes them useful as fragrances or flavouring agents. Fatty acid esters may also be used as solvents for lacquers, paints, varnishes and the like. Esters are also used as softening agents in resins and plastics, plasticizers, flame retardants, and additives in gasoline and oil. Further, esters can be used in the manufacture of polymers, films, textiles, dyes, and pharmaceuticals. Accordingly, fatty acid esters are very useful in this day and age.
Fatty acid esters may be extracted from petroleum. However, this method is energy consuming and costly. Also, it is an inefficient process because frequently the long chain hydrocarbons in crude petroleum are cracked to produce smaller monomers. These monomers are then used as the raw material to manufacture the more complex specialty chemicals. This process of cracking gasoline or petroleum is bad for the environment. Also, since the costs for these starting materials will be linked to the price of petroleum, with the expected increase in petroleum prices in the future, cost of making these fatty acid esters may also increase relative to the increase in the petroleum prices.
Due to the inherent challenges posed by petroleum, there is a need for a renewable petroleum source which does not need to be explored, extracted, transported over long distances, or substantially refined like petroleum. There is also a need for a renewable petroleum source that can be produced economically and that does not cause the environmental damage as that produced by the petroleum industry and the burning of petroleum based fuels.
Fatty acid esters may be found in several biofuels. However, the yield of the fatty acid esters from these biofuels and/or plant based fuels is low. Thus, a need exists to develop an alternate biological source of fatty acid esters. One option is to recombinantly engineer a microbial species for efficient production of fatty acid esters.
Fatty acid esters are known to be the product of a condensation reaction between an acyl-CoA molecule and an alcohol of any chain length sometimes in the presence of wax ester synthases. For example, a fatty acid ester can be the condensation product of methanol, ethanol, propanol, butanol, isobutanol, 2-methylbutanol, 3-methylbutanol, or pentanol with an acyl-CoA molecule. In some instances, fatty acid esters such as fatty acid methyl esters (“FAME”) or fatty acid ethyl esters (“FAEE”) can be produced by supplying the alcohol used in the reaction (e.g., methanol or ethanol) to the culture media. Similarly, wax esters can be produced by supplying fatty alcohols.
Most fatty acid esters have useful functions as mentioned above. One of these esters, methyl laurate, CH3(CH2)10COOCH3 a water-insoluble, clear, colourless ester, has several uses in the commercial industry including the pharmaceutical and cosmetic industry.
However, the current methods used to make fatty acid esters are inefficient as they produce a large amount of by-products that result in a waste of resources. Also, the currently available methods do not allow for selecting specific fatty acid esters. There is thus a need for more energy efficient and specific production of fatty acid esters including methyl laurate.